Theme: The numbers one, four, nine & sixteen in phrasesWhat the starred answers start with
PERFECTSQUARES [are there imperfect ones?
Odd that both 11- and 12-Down are “layered,” both natural and both hard.
Two of the four theme entries are from pop culture of the 1950’s --- my favorite time of Americana. (Vivaldi was 200 years or so before that.)
Three grins = Loved it; Two grins = Enjoyed it; One grin = A bit bland for my taste; One teardrop = Not much fun